Fixtures for holding a tool subject to grinding

ABSTRACT

A fixture for holding a tool for grinding wherein the holder is mounted for adjustment about at least one axis and is set up for grinding several distinct and different types of tool steel to achieve grinding of steel for different standard screw threads. The concepts may be utilized in a simple form for hobbyists or in a more variable form for experienced machinists.

United States Patent [1 1 Grieco Dec. 110, 19741 [54] FIXTURES FOR HOLDING A TOOL 2,767,531 10/1956 Keller 51/220 SUBJECT o GRINDING 3,512,309 5/1970 Grieco 51/218 R [76] memo 9m g gz i Primary Examiner-Harold D. Whitehead l 1 Attorney, Agent, or FirmLerner, David, Littenberg [22] Filed: Mar. 14, 1974 & Samuel Appl. No.: 451,062

[52] US. Cl 51/218 A [51] Int. Cl B24b 3/34 [58] Field of Search; 51/216, 218, 220; 269/67 [56] References Cited UNITED STATES PATENTS 2,452,089 10/1948 Wilken 269/67 X 2,735,245 2/1956 Grieco 51/220 [5 7] ABSTRACT A fixture for holding a tool for grinding wherein the holder is mounted for adjustment about at least one axis and is set up for grinding several distinct and different types of tool steel to achieve grinding of steel for different standard screw threads. The concepts may be utilized in a simple form for hobbyists or in a more variable form for experienced machinists.

2 Claims, 12 Drawing Figures FIXTURES FOR HOLDING A TOOL SUBJECT TO GRINDING BACKGROUND or THE INVENTION Fixtures forsupporting machine tools and tools subject to grinding have been developed in the past for accurately holding a tool for cutting; for example, US. Pat. Nos. 2,432,058; 2,480,618; 2,390,428; 2,351,246; 2,607,274; 2,700,854; 1,889,248; 2,448,309; 2,452,089 and 3,512,309.

However, none of the prior art devices has developed a single universal tool holder for holding tool steel which will be ground to achieve a straight square thread cutter; an off-set square thread cutter; an acme thread cutter; a US. thread cutter; a buttress thread cutter; or a British Whitworth thread cutter, all of which has accomplished without any need for changing the tool holder.

SUMMARY OF THE INVENTION Thus, the present invention contemplates the provision of a multi-purpose'tool holding fixture having a carrier-block either fixedly or rotatably secured to a base. For the more accomplished machinist, the carrier block is tilted about an axis parallel to the front edge of the base. The angle of tilt to the carrier block determines the degree of clearance or relief angles which the shaped cutting edge of a tool supported by the carrier block is provided during a grinding operation. For hobbyists or the like, this refinement need not be used, and one embodyment of the present invention calls for a fixed carrier block mounted on the base. These are provided for supporting the tool to be ground for rotation on the carrier block about an axis running perpendicular to the front face of the carrier block. Accordingly, the tools supported in the tool holding means can be inclined at select angles-so as to grind opposite faces of the cutting edge of the tool steel so as to achieve an accurate thread cutting tool. 1

A tool holding means can be especially designed blocks with supports thereon for assuring right angle support of the tool steel during the grinding operation or, in the alternative, with respect to the rod type tool steel, the rod type tool steel can be positioned in a special tool holder which indexes the steel for cutting in more than one angular position without requiring any changes in the setting of the fixture.

Additionally, the present invention contemplates a means for grinding a straight square thread cutter; an offset square thread cutter; an acme thread cutter; a US. thread cutter; a buttress thread cutter; or a British Whitworth thread cutter, utilizing the same single tool holder. Additionally, the grinding utilizing the present fixture can be achieved utilizing the front face of the grinder without placing any axial pressures on the grinder while enabling the grinderto achieve internal thread cuttingfaces on the tool steel.

The present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof, and accordingly, reference should be made to the appended claims rather than to the foregoing specification as indicated in the scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a side elevational view of a fixture built in accordance with the prior art.

FIG. 2 is a front plan view of the positioning block utilized in FIG. 1.

FIG. 3 shows the fixture of FIG. 1 utilizing grinding a U.S.S. external thread cutter on locations 33 of the carrier block of FIG. 2.

FIGS. 4 and 5 show the grinding of a U.S.S. internal thread cutter on locations 3-3 by means of an auxiliary tool holder utilized with the fixture shown in FIG. 1.

FIG. 6 shows the means by which a tool holder, when in position on 0 can grind a tool steel at any angle.

FIG. 7 shows the grinding of a boring tool by means of the auxiliary tool holder shown in FIGS. 4 and 5, when said auxiliary tool holder is positioned at 0 on the carrier block of the fixture of FIG. 1.

FIG. 8 shows a second form of the present invention in which a fixed angularly positioned carrier block is utilized.

In FIGS. 9 and 10, there is shown the simple manner in which the tool holder utilizing the fixture of FIG. 8'

utilized to grind U.S. threads.

FIGS. 11 and 12 showa straight square thread cutter and an offset square thread cutter which have been ground in accordance with the fixtures of the present invention.

The-fixture shown in FIG. 1 comprises a base 102 and a carrier block 104. The carrier block 104 supports many types of tool holders and is shown supporting a positioning block 74 and a channel member 88. The carrier block 104 is pivotally mounted on a suitable open pivotal connection 106 adjacent and parallel to the front edge of the base 102 and the carrier block 104. Thus, the carrier block 104 is adapted to be rotated about the pivot 106 and held in place by an upper limit screw threaded member 108 and a lower limit screw threaded member 110. The upper limit screw thread 108 comprises a bolt 112 connected to the base 102 by a screw thread receiving means (not shown). The carrier block 104 is slidable on the bolt 112 and has an opening through which the bolt 112 passes which is larger than the bolt 112. However, the carrier block 104 cannot move upwardly any further than is allowed by the nut 118 threaded on the upper end of the bolt 112. To prevent the carrier block from going below a lower limit, the second bolt 120 is provided, screw threaded into the carrier block 104 and adapted to have its end received within a notch formed on the upper surface of the base 102. Two springs 124 on opposite sides of the bolt 120 spring bias the carrier bar 104 upwardly. Accordingly, the spring biased springs 124 force the carrier block 104 upwardly until limited by the nut 118. The nut 188, its screw threaded downwardly, causes the carrier block 104 to move downwardly until limited by the bolt 120 touching the notch in the base 102. A given angular position is determined by a suitable pointer 128 which reads directly on a scale formed on the side surface of the base 102 to tell the operator exactly the angle of the carrier block 104 with respect to the base 102.

This fixture has been more completely described in US. Pat. No. 3,512,309 and the disclosure therein is hereby incorporated by reference.

The positioning block 74 is rotatably positioned relative to the carrier block 104 by a screw threaded securement 130 to hold the positioning block 74 in position. A tool holder 88 is screw threaded into the center of positioning block 74 and has its end 132 extending through the carrier block 104. Member 88 has suitable indexing means for fitting into holes bored into positioning block 74 in a manner to be showed in FIG. 2. The positioning block 74, as shown in FIG. 2, allows the tool holder 88 to be positioned thereon to grind square thread, U.S. thread, buttress thread, or British Whitworth threads. The index or positioning block 74 utilizes the index holes 1, 2, 3, l, 2', 3, B, W, B, and W. For example, for a square thread, one would first use the three positions l-lwith three cutting operations. For acme thread 2-2-0; and 3-3'-() for U.S. threads. It should be noted that the index holes l-l are slightly above the center line of the tool holder 74 in order to grind a tool cutter, as shown in FIG. 11, larger at a and at b. To grind an offset square thread cutter, as shown in FIG. 12, the indexing block 74 is rotated about its axis to the required angle and then the square thread cutter is ground as before. As will be noted, the offset square cutter thus ground as shown in FIG. 12 is larger at a and smaller at b. No previous positioning block has been able to achieve this type of desirable result.

By rotating the positioning or indexing block 74 180 to section B, the index holes B-B'-O may be used to achieve a buttress thread (45) cutter and W-W'-O can be used for British Whitworth threads (47, 30) cutters. When grinding any other angular cutter, the tool holder 88 is fastened to index block 74 by means of the nut 130 at the 0. Then, tool holder 88 and index block 74 are rotated as one unit to any angle and tightened by the member 130.

In FIG. 3, there is shown the indexing or positioning block 74 utilized with holder 88 to grind on a grinding wheel 90 a U.S. external thread at locations 3-3. It will be understood that both sides of the tool steel 92 can be ground by merely shifting from location 3 to location 3. The same positions 3-3 can be utilized to grind a US. internal thread cutter by means of an auxiliary tool holder 94 as shown in FIG. 4. The auxiliary tool holder 94 is substituted for the tool holder 88 and is of the type shown in my U.S. Pat. No. 3,512,309. The indexing block 74 enables one to simply grind the tool steel as shown in FIGS. 4 and 5. That is, in FIGS. 4 and 5, one sees the tool holder first in position 3 and then in position 3 to achieve the U.S. internal thread cutter.

As shown in FIG. 6, by merely fastening a tool holder on at position 0 and rotating the plate 74, a cutter can be ground at any angle. Initially, by substituting the tool holder 94 for the tool holder 88 in FIG. 6, it is possible to grind other tools such as a boring tool by means of the auxiliary tool holder.

It should be noted that in all of these operations, the grinding wheel is maintained in a manner whereby it grinds only on its outer surface so that there is little or no axial pressure thereon. It should be noted that holes 3-3 are 30 from the center line, holes 2-2 are 14, 30 from the center line, holes B-B' are 45 from the center line, holes W-W are 27, 30' from the center line, and holes l-l' are slightly above the center line (i.e., approximately 1).

In FIG. 8, there is shown another embodiment of the present invention in which a fixture is shown having a base 24 and a upright carrier block 22 integral with the base 24 and slightly tilted. A positioning block is rotatably secured to the carrier block 22 by a nut 26. A tool holder 88 is shown secured to the positioning block 30 by way of bolt 32. As in the previous embodiment, tool holder 88 has a pin at one end thereof which fits within holes 1, 2, 3, 1', 2, and 3, similar in position to the holes on carrier block 74. That is, holes l-l, I are slightly above the center line of the tool holder 88 and holes 2-2 are 14, 30 below the center line and 7 holes 3-3' are 30 below the center line. It should be noted the if the fixture 20 were to be made to grind British Whitworth and buttress threads, then suitable holes could be placed on the back of the plate 30 and the plate reversed for utilization of such indexing holes.

The positioning block 30 has square side walls ending in a semi-circular bottom face 36 graduated from to 0 and thence to 90 again. A 0 hole is also provided on the face of the positioning block 30. When the tool holder 88 is placed with its pin in the 0 hole, then the tool holder can be rotated, in a manner similar to that shown in-FIGS. 6 and 7 about the axis 42 to a desired angle of cutting. To grind a U.S. thread cutter, as shown in FIG. 9, the holder 88 is positioned with its end in hole 3 with the index plate in the vertical position as shown. The base 24 has a substantially horizontal lip 48 at the lowermost point of the positioning block 30 when the positioning block 30 is in the vertical position. When the positioning block 30 is rotated 90, its flat side surfaces abut the horizontal abutment 48. Then, as shown in FIG. 10, it is possible to grind an internal U.S. thread cutter with the index plate horizontally on the positions 3-3. Thus, utilizing the single tool holder 88, and without the need for changing tool holders as was required in the embodiment shown in FIGS. l-7, it is possible to do both internal and external U.S. thread cutting utilizing the same tool holder and the same positioning holes 3-3. This type of simple tool can be utilized by obvious or apprentice machinists to achieve the grinding of machine tools without the necessity of substantial investments in experience and parts. It will be understood that, as was described with respect to FIGS. 1-7, the other types of thread cutting can also be achieved with the positioning plate 30.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims ratherthan to the foregoing specification as indicating the scope of the invention.

I claim:

1. A fixture to supporta cutting tool for grinding comprising a base and a carrier block extending upwardly therefrom, a positioning block mounted on said carrier block, said positioning block having a flat tool holder receiving surface with a hole through said tool holder receiving surface for rotatably supporting a tool holder, indexing holes on opposite sides of said tool holder hole, a first zeroing hole positioned at a point spaced from said tool holder hole, said tool holder having a center line being formed perpendicular to a line between said zeroing hole and said tool holder hole, said positioning holes including a pair of holes positioned slightly above the center line to utilize in grinding square thread cutters, tool holder means for holding tool steel subject to grinding rotatably positioned in said tool holder hole and adapted to be removably positioned with one end of said tool holder in one of said positioning holes said base and carrier block being integral with one another, said carrier block tilting slightly from the vertical and said base extending outward under said positioning block and forming a horizontal ledge, said positioning block lowermost portion, when in a vertical position, touching said horizontal ledge, said positioning block having along the bottom thereof, when in said vertical position, a semicircular portion with a measuring scale thereon, the other portion of holes 30 below the center line. 

1. A fixture to support a cutting tool for grinding comprising a base and a carrier block extending upwardly therefrom, a positioning block mounted on said carrier block, said positioning block having a flat tool holder receiving surface with a hole through said tool holder receiving surface for rotatably supporting a tool holder, indexing holes on opposite sides of said tool holder hole, a first zeroing hole positioned at a point spaced from said tool holder hole, said tool holder having a center line being formed perpendicular to a line between said zeroing hole and said tool holder hole, said positioning holes including a pair of holes positioned slightly above the center line to utilize in grinding square thread cutters, tool holder means for holding tool steel subject to grinding rotatably positioned in said tool holder hole and adapted to be removably positioned with one end of said tool holder in one of said positioning holes said base and carrier block being integral with one another, said carrier block tilting slightly from the vertical and said base extending outward under said positioning block and forming a horizontal ledge, said positioning block lowermost portion, when in a vertical position, touching said horizontal ledge, said positioning block having along the bottom thereof, when in said vertical position, a semicircular portion with a measuring scale thereon, the other portion of said positioning block having flat side surfaces, said tool holder hole being in said other portion of said positioning block, said positioning block being rotatably mounted to said carrier block at the center of said semicircular portion to a position wherein one of said flat side surfaces abut said horizontal ledge.
 2. The fixture to support a cutting tool for grinding of claim 1 wherein said positioning holders include a second pair of positioning holes positioned 14*, 30'' below the center line and a third pair of positioning holes 30* below the center line. 